JAVA设计模式学习笔记-命令模式

案例一：遥控器
传统设计方案

Control

package com.java.test.commandmode;

public interface Control {

	public void onButton(int slot);

	public void offButton(int slot);
	
	public void undoButton();
}

Light

package com.java.test.commandmode.device;

public class Light {

	String loc = "";

	public Light(String loc) {
		this.loc = loc;
	}

	public void On() {

		System.out.println(loc + " On");
	}

	public void Off() {

		System.out.println(loc + " Off");
	}

}

Stereo

package com.java.test.commandmode.device;

public class Stereo {
	static int volume = 0;

	public void On() {
		System.out.println("Stereo On");
	}

	public void Off() {
		System.out.println("Stereo Off");
	}

	public void SetCd() {
		System.out.println("Stereo SetCd");
	}

	public void SetVol(int vol) {
		volume = vol;
		System.out.println("Stereo volume=" + volume);
	}

	public int GetVol() {
		return volume;
	}

	public void Start() {
		System.out.println("Stereo Start");
	}
}

TraditionControl

package com.java.test.commandmode;

import com.java.test.commandmode.device.Light;
import com.java.test.commandmode.device.Stereo;

public class TraditionControl implements Control {
	Light light;
	Stereo stereo;


    //传统方式存在的问题
    //如果有新的家电要加进来，这里要再写过局部变量
    //构造函数里也要修改
	public TraditionControl(Light light, Stereo stereo) {
		this.light = light;
		this.stereo = stereo;
	}

	@Override
	public void onButton(int slot) {
		// TODO Auto-generated method stub
		switch (slot) {
		case 0:
			light.On();
			break;
		case 1:
			stereo.On();
			break;
		case 2:
			int vol = stereo.GetVol();
			if (vol < 11) {
				stereo.SetVol(++vol);
			}
			break;
		}
	}

	@Override
	public void offButton(int slot) {
		// TODO Auto-generated method stub
		switch (slot) {
		case 0:
			light.Off();
			break;
		case 1:
			stereo.Off();
			break;
		case 2:
			int vol = stereo.GetVol();
			if (vol > 0) {
				stereo.SetVol(--vol);
			}
			break;
		}
	}

	@Override
	public void undoButton() {
		// TODO Auto-generated method stub
		
	}

	

}

测试类

package com.java.test.commandmode;

import com.java.test.commandmode.device.Light;
import com.java.test.commandmode.device.Stereo;

public class ControlTest {
	public static void main(String[] args) {
		Control ctl;
		Light light = new Light("Bedroom");
		Stereo stereo = new Stereo();
		ctl = new TraditionControl(light, stereo);

		ctl.onButton(0);
		ctl.offButton(0);
		ctl.onButton(1);
		ctl.onButton(2);
		ctl.offButton(2);

		ctl.offButton(1);
	}
}

命令模式
原理

使得命令的请求者和执行者解耦

Command接口

package com.java.test.commandmode.command;

public interface Command {
	public void execute();
	public void undo();
}

两个命令类的例子

LightOnCommand

package com.java.test.commandmode.command;

import com.java.test.commandmode.device.Light;

public class LightOnCommand implements Command {
	private Light light;
	
	public LightOnCommand(Light light)
	{
		this.light=light;
		
	}
	@Override
	public void execute() {
		// TODO Auto-generated method stub
		light.On();
	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub
		light.Off();
	}

}

StereoOnCommand

package com.java.test.commandmode.command;

import com.java.test.commandmode.device.Stereo;

public class StereoOnCommand implements Command {
	private Stereo setreo;
	public StereoOnCommand(Stereo setreo)
	{
		this.setreo=setreo;
	}
	
	@Override
	public void execute() {
		// TODO Auto-generated method stub
		setreo.On();
		setreo.SetCd();
		
	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub
		setreo.Off();
	}

}

NoCommand

package com.java.test.commandmode.command;

public class NoCommand implements Command {

	@Override
	public void execute() {
		// TODO Auto-generated method stub

	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub

	}

}

CommandModeControl

package com.java.test.commandmode.command;

import java.util.Stack;

import com.java.test.commandmode.Control;
import com.java.test.commandmode.device.Light;
import com.java.test.commandmode.device.Stereo;

public class CommandModeControl implements Control{
	private Command[] onCommands;
	private Command[] offCommands;
	private Stack<Command> stack=new Stack<Command>();
	public CommandModeControl()
	{
		onCommands=new Command[5];
		 offCommands=new Command[5];
		
		 Command noCommand=new NoCommand();

		 //初始化
		 for(int i=0,len=onCommands.length;i<len;i++)
		 {
			 onCommands[i]=noCommand;
			 offCommands[i]=noCommand;
		 }
		 
	}
	
	public void setCommand(int slot,Command onCommand,Command offCommand)
	{
		onCommands[slot]=onCommand;
		 offCommands[slot]=offCommand;
		
	}

	@Override
	public void onButton(int slot) {
		
		onCommands[slot].execute();
		stack.push(onCommands[slot]);
	}

	@Override
	public void offButton(int slot) {
		
		offCommands[slot].execute();
		stack.push(offCommands[slot]);
	}

	@Override
	public void undoButton() {
		// TODO Auto-generated method stub
		stack.pop().undo();
	}

}

测试类

package com.java.test.commandmode.command;

import com.java.test.commandmode.Control;
import com.java.test.commandmode.TraditionControl;
import com.java.test.commandmode.device.Light;
import com.java.test.commandmode.device.Stereo;

public class ControlTest {

	public static void main(String[] args) {
		CommandModeControl control = new CommandModeControl();
		MarcoCommand onmarco,offmarco;
		Light bedroomlight = new Light("BedRoom");
		Light kitchlight = new Light("Kitch");
		Stereo stereo = new Stereo();
		
		
		
		LightOnCommand bedroomlighton = new LightOnCommand(bedroomlight);
		LightOffCommand bedroomlightoff = new LightOffCommand(bedroomlight);
		LightOnCommand kitchlighton = new LightOnCommand(kitchlight);
		LightOffCommand kitchlightoff = new LightOffCommand(kitchlight);

		 Command[] oncommands={bedroomlighton,kitchlighton};
		 Command[] offcommands={bedroomlightoff,kitchlightoff};
			
		onmarco=new MarcoCommand(oncommands);
		offmarco=new MarcoCommand(offcommands);
		
		StereoOnCommand stereoOn = new StereoOnCommand(stereo);
		StereoOffCommand stereoOff = new StereoOffCommand(stereo);
		StereoAddVolCommand stereoaddvol = new StereoAddVolCommand(stereo);
		StereoSubVolCommand stereosubvol = new StereoSubVolCommand(stereo);

		control.setCommand(0, bedroomlighton, bedroomlightoff);
		control.setCommand(1, kitchlighton, kitchlightoff);
		control.setCommand(2, stereoOn, stereoOff);
		control.setCommand(3, stereoaddvol, stereosubvol);
		control.setCommand(4, onmarco, offmarco);

		control.onButton(0);
		control.undoButton();
		//control.offButton(0);
		control.onButton(1);
		control.offButton(1);
		control.onButton(2);
		control.onButton(3);
				
		control.offButton(3);
		control.undoButton();
		control.offButton(2);
		control.undoButton();
		control.onButton(4);
		control.offButton(4);
	}

}